/*
contributors: Patricio Gonzalez Vivo
description: bias high pass
use: <vec4|vec3|float> contrast(<vec4|vec3|float> value, <float> amount)
*/

#ifndef FNC_CONTRAST
#define FNC_CONTRAST
float contrast(in float v, in float a) { return (v - 0.5 ) * a + 0.5; }
vec3 contrast(in vec3 v, in float a) { return (v - 0.5 ) * a + 0.5; }
vec4 contrast(in vec4 v, in float a) { return vec4((v.rgb - 0.5 ) * a + 0.5, v.a); }
#endif
